Analysis of Spoke-Type Brushless Dual-Electrical-Port Dual-Mechanical-Port Machine With Decoupled Windings

Brushless dual-electrical-port dual-mecha-nical-port (BLDD) machine has become a good candidate to replace the traditional mechanical continuously variable transmission owing to its high compactness, reliability, and torque transmission capability. However, the mutual coupling between two sets of windings fed by different frequency currents leads to strong interference during both health and fault conditions, whereas the coupling effect is difficult to be reduced in the regular BLDD machine due to its operation principle. This paper presents a systematic analysis on a novel spoke-type BLDD (STBLDD) machine, aiming to eliminate coupling of windings. Using the winding function theory, the decoupling principle is analyzed in detail, and corresponding slot/pole combinations are derived. Through finite-element analysis, parameter influences on the performance of this STBLDD machine are then studied. A prototype and test bed have been designed and manufactured, and the experimental results verify the analysis results.